Since laminated glass generates only a small amount of scattering glass fragments even when subjected to external impact and broken, laminated glass is excellent in safety. As such, the laminated glass is widely used for automobiles, railway vehicles, aircraft, ships, buildings and the like. The laminated glass is produced by sandwiching an interlayer film for laminated glass between a pair of glass plates.
Moreover, laminated glass used for the opening part of vehicles and buildings is required to have high heat shielding properties.
The energy amount of an infrared ray with a wavelength of 780 nm or more which is longer than that of visible light is small as compared with an ultraviolet ray. However, the thermal action of infrared rays is large, and when infrared rays are absorbed into a substance, heat is released from the substance. As such, infrared rays are generally called heat rays. Accordingly, in order to heighten the heat shielding properties of laminated glass, it is necessary to sufficiently cut off infrared rays.
As an interlayer film including heat shielding particles for effectively cutting off the infrared rays (heat rays), the following Patent Document 1 discloses an interlayer film including a compound having a heat ray shielding function, a wavelength selective absorbing material, a polyvinyl acetal resin and a plasticizer. The compound having a heat ray shielding function is constituted of one or more kinds selected from indium tin oxide fine particles and antimony tin oxide fine particles. The wavelength selective absorbing material has a transmission profile in which the transmittance for light with a wavelength of 550 nm is 90% or more and the transmittance for light with a wavelength of 450 nm is 40% or less.
With regard to an automobile provided with laminated glass, even when a driver of the automobile does not directly view light from a headlight of an oncoming car, the driver has a psychologically unpleasant feeling due to the light passing through the laminated glass. Moreover, the visual acuity of a driver is temporarily lowered when the driver directly views light from a headlight of an oncoming car, and this may adversely affect the driving operations. In view of such problems, the enhancement in the antiglare property of laminated glass has been strongly desired. An interlayer film in which a pigment, a dye, a coloring agent or the like as a material having visible light absorbing properties is used in order to enhance the antiglare property has been known. For example, the following Patent Document 2 discloses an interlayer film including a tetraazaporphyrin compound.